linux-kernel - Re: [PATCH 06/10] remoteproc: imx

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Date:   Tue, 11 Aug 2020 15:40:56 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Peng Fan <peng.fan@....com>
Cc:     bjorn.andersson@...aro.org, o.rempel@...gutronix.de,
        robh+dt@...nel.org, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org, shawnguo@...nel.org,
        s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
        linux-imx@....com, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 06/10] remoteproc: imx_rproc: add load hook

On Fri, Jul 24, 2020 at 04:08:09PM +0800, Peng Fan wrote:
> To i.MX8, we not able to see the correct data written into TCM when
> using ioremap_wc, so use ioremap.
> 
> However common elf loader using memset.
> 
> To arm64, "dc      zva, dst" is used in memset.
> Per ARM DDI 0487A.j, chapter C5.3.8 DC ZVA, Data Cache Zero by VA,
> 
> "If the memory region being zeroed is any type of Device memory,
> this instruction can give an alignment fault which is prioritized
> in the same way as other alignment faults that are determined
> by the memory type."
> 
> On i.MX platforms, when elf is loaded to onchip TCM area, the region
> is ioremapped, so "dc zva, dst" will trigger abort.
> 
> So add i.MX specific loader to address the TCM write issue.
> 
> The change not impact i.MX6/7 function.
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  drivers/remoteproc/imx_rproc.c | 76 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 76 insertions(+)
> 
> diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> index aee790efbf7b..c23726091228 100644
> --- a/drivers/remoteproc/imx_rproc.c
> +++ b/drivers/remoteproc/imx_rproc.c
> @@ -4,6 +4,7 @@
>   */
>  
>  #include <linux/clk.h>
> +#include <linux/elf.h>
>  #include <linux/err.h>
>  #include <linux/interrupt.h>
>  #include <linux/kernel.h>
> @@ -15,6 +16,9 @@
>  #include <linux/regmap.h>
>  #include <linux/remoteproc.h>
>  
> +#include "remoteproc_internal.h"
> +#include "remoteproc_elf_helpers.h"
> +
>  #define IMX7D_SRC_SCR			0x0C
>  #define IMX7D_ENABLE_M4			BIT(3)
>  #define IMX7D_SW_M4P_RST		BIT(2)
> @@ -247,10 +251,82 @@ static void *imx_rproc_da_to_va(struct rproc *rproc, u64 da, size_t len)
>  	return va;
>  }
>  
> +static int imx_rproc_elf_load_segments(struct rproc *rproc, const struct firmware *fw)
> +{
> +	struct device *dev = &rproc->dev;
> +	const void *ehdr, *phdr;
> +	int i, ret = 0;
> +	u16 phnum;
> +	const u8 *elf_data = fw->data;
> +	u8 class = fw_elf_get_class(fw);
> +	u32 elf_phdr_get_size = elf_size_of_phdr(class);
> +
> +	ehdr = elf_data;
> +	phnum = elf_hdr_get_e_phnum(class, ehdr);
> +	phdr = elf_data + elf_hdr_get_e_phoff(class, ehdr);
> +
> +	/* go through the available ELF segments */
> +	for (i = 0; i < phnum; i++, phdr += elf_phdr_get_size) {
> +		u64 da = elf_phdr_get_p_paddr(class, phdr);
> +		u64 memsz = elf_phdr_get_p_memsz(class, phdr);
> +		u64 filesz = elf_phdr_get_p_filesz(class, phdr);
> +		u64 offset = elf_phdr_get_p_offset(class, phdr);
> +		u32 type = elf_phdr_get_p_type(class, phdr);
> +		void *ptr;
> +
> +		if (type != PT_LOAD)
> +			continue;
> +
> +		dev_dbg(dev, "phdr: type %d da 0x%llx memsz 0x%llx filesz 0x%llx\n",
> +			type, da, memsz, filesz);
> +
> +		if (filesz > memsz) {
> +			dev_err(dev, "bad phdr filesz 0x%llx memsz 0x%llx\n",
> +				filesz, memsz);
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		if (offset + filesz > fw->size) {
> +			dev_err(dev, "truncated fw: need 0x%llx avail 0x%zx\n",
> +				offset + filesz, fw->size);
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		if (!rproc_u64_fit_in_size_t(memsz)) {
> +			dev_err(dev, "size (%llx) does not fit in size_t type\n",
> +				memsz);
> +			ret = -EOVERFLOW;
> +			break;
> +		}
> +
> +		/* grab the kernel address for this device address */
> +		ptr = rproc_da_to_va(rproc, da, memsz);
> +		if (!ptr) {
> +			dev_err(dev, "bad phdr da 0x%llx mem 0x%llx\n", da,
> +				memsz);
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		/* put the segment where the remote processor expects it */
> +		if (filesz)
> +			memcpy_toio(ptr, elf_data + offset, filesz);
> +	}
> +
> +	return ret;
> +}

This is clearly the wrong approach.  What you came up with in [1] is far better,
though I would call the the operations elf_memcpy() and elf_memset().

That being said I don't know how [1] fits with this patchset.  From where I
stand a new revision is needed.

[1]. https://patchwork.kernel.org/patch/11688751/

> +
>  static const struct rproc_ops imx_rproc_ops = {
>  	.start		= imx_rproc_start,
>  	.stop		= imx_rproc_stop,
>  	.da_to_va       = imx_rproc_da_to_va,
> +	.load		= imx_rproc_elf_load_segments,
> +	.parse_fw	= rproc_elf_load_rsc_table,
> +	.find_loaded_rsc_table = rproc_elf_find_loaded_rsc_table,
> +	.sanity_check	= rproc_elf_sanity_check,
> +	.get_boot_addr	= rproc_elf_get_boot_addr,
>  };
>  
>  static int imx_rproc_addr_init(struct imx_rproc *priv,
> -- 
> 2.16.4
>